The best way to make your muscles stronger is to exercise them against resistance strong enough to damage the muscle fibers. Then, when they heal, they will be stronger.
A review of 22 studies published in the journal Human Movement in 2020 looked at how to grow larger and stronger muscles. It found that the best way for untrained people to grow muscles is to use lighter weights with more repetitions, even though most trained athletes gained more strength by using heavier weights with fewer repetitions. Lifting lighter weights with more repetitions reduces your chances of injury.